Project investigates neuroanatomical, electrophysiological and behavioral effects of variations in the internal environment. Of particular interest are the variations produced by water deprivation, hypertonic and hyperoncotic solutions, and stress. The research is aimed at discovery of the mechanisms controlling the onset, duration and termination of water regulatory responses in rats. BIBLIOGRAPHIC REFERENCES: Walters, J.K., and Harton, G.I. Supraoptic neuronal activity in rats during five days of water deprivation. Physiology & Behavior, 1974, 13, 661-667. (Copies included with this application). Harton, G.I. Nucleus circularis: is it a sense organ in the brain? I. Light microscopic and physiological studies. Anatomical Record, 1975, 181, 372. (Abstract. Copies included with this application.)